title: Spinodal decomposition and the emergence of dissipative transient periodic spatio-temporal patterns in acentrosomal microtubule multitudes of different morphology.
abstract: We have studied a spontaneous self-organization dynamics in a closed, dissipative (in terms of guansine 5'-triphosphate energy dissipation), reaction-diffusion system of acentrosomal microtubules (those nucleated and organized in the absence of a microtubule-organizing centre) multitude constituted of straight and curved acentrosomal microtubules, in highly crowded conditions, in vitro. Our data give experimental evidence that cross-diffusion in conjunction with excluded volume is the underlying mechanism on basis of which acentrosomal microtubule multitudes of different morphologies (straight and curved) undergo a spatial-temporal demix. Demix is constituted of a bifurcation process, manifested as a slow isothermal spinodal decomposition, and a dissipative process of transient periodic spatio-temporal pattern formation. While spinodal decomposition is an energy independent process, transient periodic spatio-temporal pattern formation is accompanied by energy dissipative process. Accordingly, we have determined that the critical threshold for slow, isothermal spinodal decomposition is 1.0 ± 0.05 mg/ml of microtubule protein concentration. We also found that periodic spacing of transient periodic spatio-temporal patterns was, in the overall, increasing versus time. For illustration, we found that a periodic spacing of the same pattern was 0.375 ± 0.036 mm, at 36 °C, at 155th min, while it was 0.540 ± 0.041 mm at 31 °C, and at 275th min after microtubule assembly started. The lifetime of transient periodic spatio-temporal patterns spans from half an hour to two hours approximately. The emergence of conditions of macroscopic symmetry breaking (that occur due to cross-diffusion in conjunction with excluded volume) may have more general but critical importance in morphological pattern development in complex, dissipative, but open cellular systems.
authors.affiliation: Brain and Mind Research Institute, Sydney Medical School, The University of Sydney, Sydney NSW 2050, Australia. bvlado@physiol.usyd.edu.au
authors.forename: Vlado A
authors.initials: VA
authors.lastname: Buljan
authors.forename: R M Damian
authors.initials: RM
authors.lastname: Holsinger
authors.forename: D
authors.initials: D
authors.lastname: Brown
authors.forename: J J
authors.initials: JJ
authors.lastname: Bohorquez-Florez
authors.forename: B D
authors.initials: BD
authors.lastname: Hambly
authors.forename: E J
authors.initials: EJ
authors.lastname: Delikatny
authors.forename: E P
authors.initials: EP
authors.lastname: Ivanova
authors.forename: R B
authors.initials: RB
authors.lastname: Banati
mesh_terms: D000818:Animals; D002417:Cattle; D018385:Centrosome / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D008868:Microtubule Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D062211:Spatio-Temporal Analysis
chemical_list: D008868:Microtubule Proteins; D006160:Guanosine Triphosphate